The aims of this project are: 1) to study the in vitro metabolism of sterols and steroids in the brain, 2) to search for 24-hydroxycholesterol and 25-hydroxycholesterol in steroidogenic tissues and to study their metabolism in those tissues and 3) to determine whether hydrophobic effects influence the nature or kinetics of the reactions of the naturally occurring lipoidal derivatives of steroids. The latter goal aims to substantiate the hypothesis that suggests that the fatty acid portions of these molecules are in aqueous media, in close association with the carbon atoms of the steroidal moeity. In such conformations the polyunsaturated systems of the carboxylic acids may modify the reactivities of the C atoms of the steroid. The methods required for these studies include radioisotope technology using labeld steroids, in vitro incubations with various tissue preparations, isolation techniques involving various chromatographic procedures (TLC, partition chromatography, HPLC, etc) and spectrometric techniques, such as UV, IR and MS. One objective of this research plan is to explore the possibility that steroid hormones are biosynthesized in the brain. Another goal is to examine the products formed when the brain sterols, 24-hydroxycholesterol and 25-hydroxysterols, are incubated with various preparations of steroidogenic tissues such as adrenals, testes and ovaries. Finally we intended to study the behavior of the naturally occurring lipoidal derivatives when these nonpolar compounds are exposed to the enzyme systems present in steroidogenic glands. Success with any of these three plans could provide important, new information about steroid hormone biochemistry.